Power tools and other portable electrical equipment are generally equipped with relatively short electrical power cords having a male plug at the end thereof. However, a longer power cord is often required to provide power to the tools in an area remotely located from an electrical outlet. As a result, power tools are frequently connected to remote outlets via extension cords. An extension cord is an electric cord fitted with a male plug at one end and a female receptacle at the other end. The female receptacle end of the extension cord is mated with the male plug of the power tool cord. The male plug of the extension cord is inserted into a conventional outlet, providing an electrical connection between the outlet and the power tool. Additionally, numerous extension cords may be connected together, extending the distance of the electrical connection between power tools and remote outlets.
Electrical cords maintain a plugged together relationship between prongs of the male plug and corresponding receptacles of the female socket through friction. The friction between the plug and socket is adequate to maintain the electrical cords in a plugged together relationship when the cords are stationary. However, the friction between the plug and socket may be insufficient to hold the electrical cords together when the cords are moved around, such as at a construction site. In the latter situation, the insufficient friction between the plug and socket causes them to accidentally separate, interrupting the flow of electricity to the power tool. The interruption of the flow of electricity to the tool can be annoying and time consuming, and sometimes possibly dangerous in certain situations. For example, if the power is intermittent because of a poor connection, the operator of the tool may believe that the tool is not powered when in fact power could be reapplied at any time.
Numerous inventions have been devised to solve the problem of accidental separation of the male plugs and female sockets of electrical cords. One solution has been the use of a device that clamps the male plugs and female sockets together. A device that clamps plugs and sockets together is disclosed in U.S. Pat. No. 4,183,603, issued to Carmo. The Carmo patent shows various mechanisms for holding the connection between the plugs and socket, including, for example, a thumbwheel which is rotated to firmly press the male plug and the female socket together. Another device that holds the connection between plugs and socket is disclosed in U.S. Pat. No. 3,383,639, issued to Anderson et al. The Anderson patent shows an extension cord coupling clamp conforming around the ends of the male plugs and female sockets to keep them connected. These devices, however, place an undue amount of strain on the connection of the plugs and sockets, to the wire, and, therefore, may damage the plugs and sockets or the electrical cords.
Accordingly, some devices have been constructed to relieve, at least partially, the strain on the connection by clamping the electrical cords without imposing unnecessary forces on the plugs and sockets themselves. For example, a strain relief device having a pair of clamps connected by a threaded rod extension is disclosed in U.S. Pat. No. 3,609,638, issued to Darrey. Each clamp securely grips the electrical cord with the connected male and female ends disposed therebetween. Such devices which employ a clamp or similar apparatus may damage the electrical integrity of the conductors, the insulation, or the cover of the extension cord.
Other strain relief devices have been constructed without the use of potentially damaging clamps. In U.S. Pat. No. 5,255,866, issued to Campolo, a stain relief device is disclosed consisting of a rigid hollow cylinder with two rigid flanges extending at opposite ends of the cylinder. The joined plug and socket of two electrical cords are positioned inside the cylinder. Each respective cord is bent back through slots in the flanges and wound around the cylinder between the flanges, thereby transmitting tension between the electrical cords to the cylinder and flanges. However, these devices waste a considerable amount of the extension cord due to the necessity of winding the cord around the device to transfer the strain from the cord to the device. In addition, devices such as the one disclosed by Campolo prevents visual inspection of the connection between the two cords.
A device that provides for visual inspection of the connection between the two electrical cords without the use of clamps and without inducing unnecessary forces on the plugs and sockets themselves and without wasting a considerable amount of the extension cord is disclosed in U.S. Pat. No. 5,582,524 issued to Sanner et al. The Sanner patent discloses a device comprised of a base member having a pair of eyelets, each eyelet defining an opening of a size for allowing the passage of a looped electrical cord. A pair of hook members are secured to the base member and spaced from the eyelets. Each hook member is shaped for receiving the looped portion of the electrical cord.
However, the Sanner device, although a vast improvement over the previous art, may still not be optimal in terms of minimizing the length of the electrical cord necessary to secure the electrical cord with the Sanner device.
Also, the Sanner device provides for a one-to-one connectivity; i.e., one male plug connected to one female socket. Possibly of more use in the setting of a busy commercial construction site is one-to-plurality connectivity; e.g., an active electrical cord runs from the electrical supply to the device which then serves as a "tap" to provide electrical power to a plurality of other electrical cords. It is important that all of the electrical cords connected to the tap are maintained in a plugged together relationship.
Therefore, it is an object of this invention to provide a device with a practical construction for maintaining the connection between male plugs and female sockets while not imposing undue strain on the plugs and sockets.
It is also an object of the present invention to provide a device with a practical construction for preventing the separation of two electrical cords which minimizes the amount of electrical cord necessary to secure the cord with the device.
Another object of the invention is to provide a device with a practical construction for preventing the separation of two electrical cords which provides for the complete elimination of any slippage of the electrical cords out of the cord securement member.
Another object of the invention is to provide a device with a practical construction for preventing the separation of two electrical cords which is able to function as a "tap" to provide electrical power to a plurality of electrical sockets.
Another object of the present invention is to provide a device as described above which can be manufactured easily and at a low cost from commercially available materials.
Another object of the present invention is to provide a device as described above which prevents the cords from becoming worn or damaged.
Another object of the present invention is to provide a device as described above which allows the user to easily visually inspect the integrity of the connection of the electrical cords.
These and other objects and advantages of the present invention will become apparent from the following description.